José Iniesta-Jaén’s research while affiliated with University of Alicante and other places

In order to improve their adhesion to polyurethane adhesives, three unvulcanized block styrene-butadiene-styrene (SBS) rubbers with styrene contents between 33% and 55% were surface-treated with solutions of 2 wt% trichloro-isocyanuric acid (TCI) in ethyl acetate. The joint strength was estimated using T-peel tests and the failed surfaces were analyzed to assess the locus of failure. The failed surfaces were analyzed using ATR-IR spectroscopy, contact angle measurements, XPS, and SEM. An unexpected trend in the joint strength was obtained because the locus of failure depended on both the styrene content and the mechanical properties of each SBS rubber. A mixed mode of failure was obtained in joints produced with S 1 rubber (33 wt% styrene content), whereas failure in the chlorinated layer was observed with S3 rubber (55 wt% styrene content); cohesive failure in the adhesive was found for the joints produced with S2 rubber (44 wt% styrene content).

Oxalic acid (OA) solutions in butanone/alcohol mixtures were used as surface treatment of synthetic vulcanized styrene-butadiene rubber (SBR). Several experimental variables were considered (OA concentration, nature and amount of the alcohol in the solvent mixture, roughening of rubber). The treatment with oxalic acid increases the T-peel strength of adhesive joints. The effectiveness of the surface treatment depends on the rubber formulation and is mainly due to the removal of antiadherent compounds on the rubber surface.